Account for provider config weight when kicking off a request in Fall…

…backProvider (ethers-io#4298).

src.ts/_tests/test-providers-fallback.ts

@@ -4,6 +4,7 @@ import {
  isError, makeError,
 
  AbstractProvider, FallbackProvider, Network,
+ ZeroAddress
 } from "../index.js";
 
 import type {
@@ -93,3 +94,68 @@ describe("Test Fallback broadcast", function() {
  });
  });
 });
+
+describe("Test Inflight Quorum", function() {
+ // Fires the %%actions%% as providers which will delay before returning,
+ // and returns an array of arrays, where each sub-array indicates which
+ // providers were inflight at once.
+ async function test(actions: Array<{ delay: number, stallTimeout: number, priority: number, weight: number }>, quorum: number): Promise<Array<Array<number>>> {
+ const inflights: Array<Array<number>> = [ [ ] ];
+
+ const configs = actions.map(({ delay, stallTimeout, priority, weight }, index) => ({
+ provider: new MockProvider(async (r) => {
+ if (r.method === "getBlockNumber") { return 1; }
+ if (r.method === "getBalance") {
+ // Add this as inflight
+ let last = inflights.pop();
+ if (last == null) { throw new Error("no elements"); }
+ inflights.push(last);
+ last = last.slice();
+ last.push(index);
+ inflights.push(last);
+
+ // Do the thing
+ await stall(delay);
+
+ // Remove as inflight
+ last = inflights.pop();
+ if (last == null) { throw new Error("no elements"); }
+ inflights.push(last);
+ last = last.filter((v) => (v !== index));
+ inflights.push(last);
+
+ return 0;
+ }
+ console.log(r);
+ throw new Error(`unhandled method: ${ r.method }`);
+ }),
+ stallTimeout, priority, weight
+ }));
+
+ const provider = new FallbackProvider(configs, network, {
+ cacheTimeout: -1, pollingInterval: 100,
+ quorum
+ });
+ await provider.getBalance(ZeroAddress);
+
+ return inflights;
+ }
+
+ // See: #4298
+ it("applies weights against inflight requests", async function() {
+ this.timeout(2000);
+
+ const inflights = await test([
+ { delay: 50, stallTimeout: 1000, priority: 1, weight: 2 },
+ { delay: 50, stallTimeout: 1000, priority: 1, weight: 2 },
+ ], 2);
+
+ // Make sure there is never more than 1 inflight provider at once
+ for (const running of inflights) {
+ assert.ok(running.length <= 1, `too many inflight requests: ${ JSON.stringify(inflights) }`);
+ }
+ });
+
+ // @TODO: add lots more tests, checking on priority, weight and stall
+ // configurations
+});

src.ts/providers/provider-fallback.ts

@@ -684,7 +684,7 @@ export class FallbackProvider extends AbstractProvider {
  // Add any new runners, because a staller timed out or a result
  // or error response came in.
  for (let i = 0; i < newRunners; i++) {
- this.#addRunner(running, req)
+ this.#addRunner(running, req);
  }
 
  // All providers have returned, and we have no result
@@ -759,8 +759,12 @@ export class FallbackProvider extends AbstractProvider {
 
  // Bootstrap enough runners to meet quorum
  const running: Set<RunnerState> = new Set();
- for (let i = 0; i < this.quorum; i++) {
- this.#addRunner(running, req);
+ let inflightQuorum = 0;
+ while (true) {
+ const runner = this.#addRunner(running, req);
+ if (runner == null) { break; }
+ inflightQuorum += runner.config.weight;
+ if (inflightQuorum >= this.quorum) { break; }
  }
 
  const result = await this.#waitForQuorum(running, req);